The problem with your premise is that there is a lot of truth to it, but there is also a lot of misleading. Sure enough, these famous pastors have said negative things about other pastors or belief systems, but upon closer observation, there might actualy be some reason for it. If the definiton of a Christian is, as you have posted: "one who professes belief in the teachings of Jesus Christ", then it really should not come as any surprise that when large groups of the so-called faithful stray from the actual teachings of Christ, someone will get up and call them out on it. The reason for that is the concern that as the organizations in error promote their versions of Christianity, people who are too new or not knowledgeable will be 'trapped' by them.
In the case of the Catholic and Mormon faiths, there is a lot more in their respective faiths that is not in the Bible alone. Both faiths use either extra-Biblical books or teachings in direct contradiction to the teachings of Jesus or the Bible. This sends many Bible teachers off to defend the Bible, because they feel it is their duty to do so.
On the other hand, it is far from true that no two ministers on the planet can agree on what Christianity is. If you see the milllions of believers around the world that gather together to worship, this becomes evident. Furthermore, there is no greater assurance for any Christian than knowing that he can go anywhere in the world where there are other Christians, and be with 'family'
There is way more that binds Christians together in huge numbers than divide them.Of course, if someone is looking to find fault, they will find it and miss the forest for the trees, This again, is no surprise to the Christian.